In this investigation, cementitious materials, such as blast furnace slag, fly ash and silica fume, were globally estimated from the viewpoint of high performance concrete. In addition, as another materials, volcanic ash was investigated for utilization of concrete.To reduce unit powder content of high fluidity concrete by controlling powder's particle size distribution, the ranges of viscosity and yield value of mortar to be part of concrete, which satisfy the high fluidity, nonsegregating property and passability between steel bars, were clarified. And the physical characters of powser, which can satisfy the ranges with the minimum unit powder content, were clarified. Besed on the results, new cementitious powder which can produce high fluidity concrete with low unit powder content was presented.Investigations were planned to make clear that relationship between size distribution of powders and rheological properties (yield value and viscosity) of mortar which have direct effects upon properties of high fluidity coucrete. As the results of this study, they were found that yield value of mortar is influenced by n-value of the Rosin-Rammler which is the main factor of amount of excess water in mortar, and that viscosity of mortar is influenced by blaine surface area, which it is reason of the effect obtained by combining absorption of superplasticizer and thickness of water film.(2)各種混和材の混合使用に関する検討においては,フライアッシュとシリカフュームを混合使用した場合,(1)水結合材比が0.3程度以下の配合条件においては,高性能AE減水剤を用いることにより,高い流動性を持つコンクリートを製造することが可能であること,(2)長期材齢においては,混和材を用いない普通コンクリートよりも高強度が得られること,などを明らかにした。(3)その他の無機系微粒子材料コンクリートへの適用可能性に関する検討においては,雲山普賢岳およびフィリピンピナツボ火山よりそれぞれ採取された火山灰を用いたモルタルを作製し,その流動性ならびに硬化体の強度特性を測定した。その結果,火山灰の材料的性質は,採取地によらず,フライアッシュに近似した化学組成を持つこと,セメントを火山灰で 10%程度置換した場合のモルタルの流動性ならびに強度特性は,フライアッシュを 25%程度置換したモルタルのものとほぼ同等であることなどを明らかにした。